1. Field of the Invention
The present invention is directed to producing low DE starch hydrolysates, which involves fractionating a starch hydrolysate having a DE greater than about 18 using a nanofiltration membrane under nanofiltration conditions effective to result in low DE starch hydrolysate having a DE of less than about 25; resultant low DE starch hydrolysate products; blends of such low DE starch hydrolysates with other substances; use of low DE starch hydrolysate products having a DE of less than about 25 and a polydispersity of less than about 5 as a binder and/or filler for solid and liquid delivery systems; producing an enlarged, dust-free, flowable granulated powder from such low DE starch hydrolysates; use of such low DE starch hydrolysates in coating solid forms.
2. Description of the Related Art
Maltodextrins, a low DE starch hydrolysate with a dextrose equivalent (DE) of not more than about 20, e.g., 4 to 20, have bland taste, low sweetness, and low hygroscopicity. Such products are useful as bases for the preparation of food items as well as for bodying agents and as additives having non-sweet, water-holding, non-hygroscopic characteristics. Other applications include their use as a carrier for synthetic sweeteners, as spray drying adjunct, as bulking, bodying or dispersing agents, as moisture holding agents, and as energy source in sports drinks.
Most commercially available maltodextrins in the world market produced by known technology are in the solid form or crystalline form due to retrogradation or haze formation or microbial instability in liquid form. However, there is a demand for a maltodextrin in its liquid form, which exhibits extreme clarity, low viscosity, and will not develop retrogradation upon storage at room temperature.
There has been low DE liquid maltodextrins produced using conventional processes, such as enzyme conversion, chromatographic fractionation and membrane fractionation. However, the products produced suffered disadvantages including instability in liquid form or high viscosity.
U.S. Pat. Nos. 3,974,033 and 3,974,034 disclose methods to produce a low DE maltodextrin and improve stability by enzymatic hydrolysis of oxidized starch. The maltodextrin is characterized as being haze-free for long period of time at high solids concentration. The maltodextrin is prepared by first liquefying a highly oxidized starch with acid or enzyme to a DE not substantially above about 7; and, in a subsequent step, converting the oxidized and liquefied starch with a bacterial alpha-amylase enzyme preparation to achieve a maltodextrin product having a DE not substantially above about 20.
U.S. Pat. No. 4,298,400 discloses another enzyme hydrolysis method to produce non-haze low DE liquid starch hydrolysates. The product, prepared by two step hydrolysis both using bacterial alpha amylase, has a descriptive ratio higher than 2.0, and, therefore, exhibits non-haze property.
U.S. Pat. No. 4,840,807 discloses a fractionation method to produce liquid low DE branched maltodextrins. The process comprises the steps of reacting alpha-amylase with starch to produce a starch hydrolysate in the DE range of 10 to 35, and then contacting the resulting saccharified solution with a gel-type filter agent, thereby selectively fractionating the branched dextrin and linear oligo-saccharides. The gel-type filtering agent is an ion exchange resin and the fractionation system is a simulated moving bed. The resulted branched oligosaccharides has a mean molecular weight of from about 800 and to about 16,000 with a corresponding DE from about 20 to about 1.
Membrane separation is known to fractionate polysaccharides of sugars. Waniska et al. (Journal of Food Science, Vol. 45 (1980), 1259) discloses the fractionating ability of three ultra filtration (UF) membranes compared with gel permeation and chromatography for separating oligosaccharides (DP5-20) from lower molecular sugar. Birch et al. (Die Starke 26. Jahrg. 1974/Nr.7, 220) discloses the fractionation of glucose syrups by reverse osmosis (RO) which offers a means for the manufacture of several new types of syrup, and which enables entire groups of sugars to be eliminated under selected conditions. Products in the range 43-80 DE or 15-43 DE can be obtained using suitable combinations of different membranes. Kearsley et al. (Die Starke 28. Jahrg. 1976/Nr. 4, 138) discloses the reverse osmosis(RO) of glucose syrups and ultra filtration (UF) operations to isolate specific groups of sugars, high or low molecular weight or both, from the syrup. Sloan et al. (Preparative Biochemistry, 15(4), 1985, 259-279) discloses the molecular filtration of ultra filtration (UF) membranes to concentrate oligosaccharides with degrees of polymerization above 10 from corn starch hydrolysate. It is not believed that any of these processes has been used to make a non-retrograded maltodextrin having low viscosity.
Those concerned with low DE starch hydrolysates recognize the need for an improved low DE starch hydrolysate, particularly in liquid form, and more particularly, in blends thereof with other substances.
It is well known that in order to form an acceptable tablet a binder and/or filler must have several attributes. Ideally, a binder or filler would possess the following properties: (1) inertness, non-reactiveness; (2) high degree of plastic deformation; (3) low elastic modulus; (4) high dislocation density; (5) tasteless and odorless; (6) non-hygroscopic or slightly hygroscopic; (7) chemically and physically compatible with other ingredients such as lubricants, flow and disintegration aids, colorants, dyes; (8) fast disintegration if desired ; (9) no bioavailability hindrance or delay; (10) aging stability; and/or (11) a high loading/carrying capacity for active ingredients. Those principles arc described in U.S. patent applications Ser. No.: 4,551,177; 5,057,321, 3,873,694, 4,439,453; in WO 99/09959, WO 97/48392; EP 0783300; WO 99/08659.
Currently, there are many available binders and fillers including vehicles such as spray-dried lactose, pregelatinized starch, microcrystalline cellulose (MCC), sorbitol, hydroxypropylmethyl cellulose (HPMC). However, many binders and fillers have well known disadvantages. For example, lactose is known to discolor upon contact with amines, phosphates, lactates, or moisture. MCC requires a dry storage atmosphere for fluffiness and to obtain good tabletting results. Starches often lead to discoloration and high viscosity. HPMC and other cellulosics can impart a slimy taste, Taxation effects, high foam and increased color. Accordingly, those concerned with the art of formulating delivery systems recognize the need for binders and fillers with improved functionality, and stability upon aging.
The present invention is directed to a process for producing a low DE starch hydrolysate, which involves fractionating a starch hydrolysate having a DE greater than about 18 using a nanofiltration membrane, preferably selected from the group consisting of Teflon membranes, stainless steel membranes, ceramic membranes, and polymeric membranes; and/or having a molecular weight cut-off of less than about 4,000 daltons, under nanofiltration conditions effective to result in low DE starch hydrolysate having a DE of less than about 25.
In accordance with the present invention, such nanofiltration membranes preferably comprise a thin film composite membrane, wherein the preferred thin film composite membrane is selected from the group consisting of polyamide membranes and polysulfonated polysulfone membranes.
In one embodiment of the present invention, the low DE starch hydrolysate comprises a liquid, low DE starch hydrolysate having a DE of less than about 25 and a polydispersity index of less than about 5. The liquid, low DE starch hydrolysate preferably comprises a dry solids content within a range of about 50% to about 85%, and/or a viscosity at 70% dry solids content and at 25xc2x0 C. of less than about 30,000 centipoise. The liquid low DE starch hydrolysate preferably is substantially non-retrograding and microbial stable.
The present invention also involves hydrogenating, and/or derivatizing, and/or drying the low DE starch hydrolysate of the present invention to result in an hydrogenated, and/or derivatized, and/or dry low DE starch hydrolysate.
It is accordingly an objective of the present invention to provide a nanofiltration membrane process for producing low DE starch hydrolysates having a DE less than about 25 and a polydispersibility index of less than about 5, particularly in their liquid form which are eventually substantially retrogradation free, and have lower viscosity at high dry solids compared to conventional products.
The liquid form and its characteristics of low viscosity are particularly suitable for drying, preferably by spray drying or extrusion, the liquid to result in a solid or substantially dry product.
The present invention is also directed to a process for producing solid forms comprising the steps of forming an aqueous composition comprising at least one member selected from the group consisting of low DE starch hydrolysate of the present invention, in its non-hydrogenated, or hydrogenated, or derivatized form; drying said aqueous composition to a moisture content of less than about 10% to result in a substantially dry low DE starch hydrolysate composition; and shaping said dry low DE starch hydrolysate composition to result in a solid form.
In one embodiment of the present invention, the process for producing solid forms further comprises a step of granulating (during and/or after the drying step) the substantially dry low DE starch hydrolysate composition to result in a granular substantially dry low DE starch hydrolysate composition. As used herein, granulating refers to the process of particle size enlargement and may be accomplished by granulation, agglomeration, compaction, or other suitable means.
In another embodiment of the present invention, the aqueous composition further comprises an effective concentration of at least one other ingredient.
It is yet another objective of the present invention to provide a process for producing a coated solid form, comprising the steps of: forming an aqueous composition comprising at least one member selected from the group consisting of low DE starch hydrolysate of the present invention in its non-hydrogenated, or hydrogenated, or derivatized form; and applying to the solid form said aqueous composition in order to form a coated solid form.
In one embodiment of the present invention, the aqueous composition further comprises an effective concentration of at least one ingredient selected from the group consisting of sugars; sugar alcohols; cellulosic polymers such as microcrystalline cellulose, hydroxypropylmethyl cellulose, hydroxyethyl cellulose; polymeric ingredients such as polyvinyl pirrolydone (PVP) of varied molecular weight from 20,000 to 2,000,000; starches (modified and/or pregelatinized), protein based ingredients such as gelatine and pectin, preservatives, flavours, colourings.
It is yet another objective of the present invention to provide a process for producing a substantially dry granular low DE starch hydrolysate composition comprising the steps of: forming an aqueous composition comprising at least one member selected from the group consisting of low DE starch hydrolysate, in its non-hydrogenated, or hydrogenated, or derivatized form; drying said aqueous composition to a moisture content of less than about 10% to result in a substantially dry low DE starch hydrolysate composition; and granulating the low DE starch hydrolysate composition to result in a granular substantially dry low DE starch hydrolysate product.